Picture Post: Shamrock and roll

It's the time of the year when much of the world proclaims itself Irish or honorary-Irish, and when a legendary fifth-century figure is celebrated with the ritual consumption of Guinness and wearing of ludicrous green hats. The fact that practically nothing concrete is known about St Patrick did not stop them from sporting shamrocks in Australia, dressing up as leprechauns in Savannah, Georgia, and waving shillelaghs in Argentina.

In Chicago, they dyed the river green while in many Irish bars they served green beer. In dozens of cities, in Ireland and around the globe, they staged parades and festivals. More than 30 million Irish Americans had cause to celebrate, but the unlikeliest of locales – New Delhi, Tokyo, Moscow and Abu Dhabi – also found Celtic roots.

St Patrick's Day, extolling Ireland's patron saint, is not sophisticated. And it's not supposed to be. It is the day when kitsch becomes cool, when national pride is expressed with the Irish preference for the informal, when ceremonial is combined with lack of ceremony.

Today, the event is a mixture of the carnival and the coolly commercial. And the Irish political establishment capitalises on the event – almost the entire cabinet has fanned out across the globe, leaving only two ministers minding the shop in Dublin.

According to prime minister Bertie Ahern: "It provides a framework to showcase modern Ireland all over the world. It is used unashamedly by us as a marketing opportunity."

This approach helps explain why Beijing has just hosted its first ever St Patrick's Day parade, with 5,000 people lining the route.

There, as elsewhere, the event fulfilled a series of functions, encouraging new trade while proudly proclaiming to the world the joy of being Irish.

And Ireland itself has the most to celebrate: no other country has a national day which is such an international asset.